The Blacksteel Blade costs 55 bronze to purchase from the sword market.
The centre of the blade is a dark grey colour, along with the hilt and pommel, the handle is a dark blue colour, while the bevels of the blades are silver.
You need to be 1h sword level 4 to be able to use this sword.
Location of the sword market is in Kyanite Village, behind the spawn.
The Blacksteel Blade does a total damage of 75.